Conventional 35 mm film cartridges comprise a cylindrical metal shell with formed lips covered by strips of velvet material which serve as a lightlock to prevent light from entering the cartridge and exposing the enclosed spool of film, plus annular metal end caps staked onto each end of the metal shell. As shown in commonly assigned U.S. Pat. No. 2,940,232, the trailer end of the film is taped to the core of the spool. The spool of film is wound and then inserted axially into a preformed assembly of the metal shell, lightlock and one end cap, with the leader of the film strip extending through the lightlock, after which the second end cap is installed to complete the cartridge. An alternative approach to loading such a cartridge is shown in U.S. Pat. Nos. 3,586,258 and 3,910,516 which describe processes in which a guide tongue is inserted between the strips of velvet lightlock material of a fully assembled cartridge. An end of a film strip is inserted along the guide tongue and engaged with features on the spool of the cartridge, after which winding proceeds through the lightlock to the spool.
Various modifications to this familiar film cartridge have been suggested in the literature over the years as results of efforts to simplify and improve the structure of the cartridge and the apparatus and process for assembling and loading the cartridge. Recently, however, an improved cartridge has been developed which comprises a pair of mating cartridge halves, which may be injection molded and which totally enclose a spool for film. An elongated, axial slot is provided between the halves to permit film to be inserted into or withdrawn from the cartridge, the slot being provided with a pivotable lock or door to replace the conventional velvet lightlock. One example of a cartridge of this general type is shown in U.S. Pat. No. 4,333,615.
FIG. 1 illustrates a web 10 of a material such as photographic film, the web having longitudinal edges 12, 14 extending between a leader end 16 which will extend first from the completed film cartridge to engage a camera, and a trailer end 18 which will engage the spool for the film. A plurality of imaging areas 20 are spaced along web 10 between ends 16, 18 in the familiar manner. Leader end 18 is formed of a central tongue portion 22 having punched through its thickness a pair of elongated slots 24. A locator feature, such as an edge aperture 25, may be provided near trailer end 18 for a purpose to be discussed subsequently.
A spool 26 comprises a central core 28 having near its ends a pair of end flanges 30, 32 spaced slightly further apart than the width of web 14. Between end flanges 30, 32, core 28 is provided with an axial recess from which extend a pair of axially spaced, circumferentially curved hooks 34, 36 for engaging elongated slots 24. Each end of spool 26 is provided with an axially extending hub 38 and at least one of such hubs comprises a central bore having a radial notch 40 or similar feature for engaging a conventional quill shaft which rotates the spool to wind the web.
As those skilled in the art will understand from FIG. 1, web 14 may be attached to spool 26 simply by passing hooks 34, 36 through slots 24 and slipping the tip of tongue 22 beneath the hooks. Once this is done, spool 26 may be rotated in the direction of the arrow to wind web 14 onto the spool. If web 14 is made from a material which tends to curl back on itself longitudinally, as do many photographic film materials, web 14 may be oriented to curl toward spool 26, which tends to ease engagement of hooks 34, 36 with slots 24.
FIGS. 2 and 3 illustrate a cartridge into which a web of material such as photographic film may be easily and efficiently wound using the apparatus and method of the present invention. However, the apparatus and method of the invention also may be used with conventional film cartridges of the types mentioned previously. A first, essentially semi-cylindrical cartridge half 50 and a mating, essentially semi-cylindrical cartridge half 52 are provided which may be separate pieces or may be joined by an axially extended living hinge 54. Essentially semi-circular end walls 56, 58 are provided at the opposite ends of halves 50, 52, each end wall including a semi-circular aperture 60, 62 for receiving and rotatably supporting one of hubs 38. Half 50 comprises a longitudinally extended, radially outwardly projected lip 64. A longitudinally extended door or light valve 66 is supported rotatably on lip 64 by means of a pair of axially spaced trunnions 68, only one of which is visible in the illustrations. A longitudinally extended lip 70 of door 66 rests in the illustrated closed position of the door against a longitudinally extended stop surface 72 formed in lip 64. By means not illustrated, door 66 may be engaged from outside the assembled cartridge and rotated to an open position illustrated schematically in FIG. 5. Half 52 comprises a longitudinally extended, radially outwardly projected lip 74. A longitudinally extended slot or opening 76 is formed in lip 74 and is positioned opposite door 66 when halves 50, 52 are assembled about an empty spool 26 as shown in FIG. 3.
To wind web 14 into the assembled cartridge, door 66 first is rotated to its open position. Trailing end 18 is then inserted into the cartridge through slot 76 and slots 24 are engaged with hooks 34, 36. The problem of reliably achieving this engagement in a high speed production environment is solved in accordance with the present invention. In FIG. 3, the initial path 78 of web 14 at the beginning of winding onto spool 26 is shown to extend tangentially to core 28. However, as winding proceeds in the direction of arrow w, the increasing diameter of the wound material will cause the path of web 14 to move steadily toward the edge of slot 76, eventually resulting in scraping of the web if the position of the cartridge and the angle of the web remain unchanged. The problem of avoiding such scraping is solved in accordance with one aspect of the present invention by causing relative movement between initial path 78 and the cartridge in the direction of arrow r, so that the final path 80 of web 14 is essentially tangent to the as-wound diameter but is spaced safely from the edge of slot 76.